1. Field
The present disclosure relates generally to an improved data processing system and, in particular, to a method and apparatus for controlling a vehicle.
2. Background
Aerial vehicles may include navigation systems to guide these types of vehicles without direct and/or continuous human control. Navigation systems generate information used to guide an aerial vehicle. This information may be used by a human operator and/or a guidance system.
Both types of systems require airframe state data to operate the aerial vehicle. Airframe state data describes various parameters about an aerial vehicle around the aerial vehicle during flight. This airframe state data is used by pilots and/or guidance systems to make operational decisions and control actions regarding an aerial vehicle. Airframe state data may include, for example, total pressure, static pressure, angle of attack, angle of side slip, surface velocity, pitch rate, and/or other suitable airframe data.
An inertial measurement unit (IMU) is an example of one device that may be used to obtain some types of air data. An inertial measurement unit generates data that allows a guidance system or navigation system to track the position of an aerial vehicle. An inertial measurement system detects the current rate of acceleration along with other rotational attributes. These rotational attributes include, for example, pitch, roll, and yaw. This information is used to calculate a current position for an aerial vehicle.
With aerial vehicles, it is desirable to have backups or alternative methods to identify the position of an aerial vehicle if an inertial measurement unit fails and/or becomes less reliable. Less reliable data and/or failure of inertial measurement units may cause an aerial vehicle to miss a destination. For example, a second inertial measurement unit may be included in the aerial vehicle to provide redundancy. Inertial measurement units, however, add to the weight and/or expense of an aerial vehicle.
Although redundant systems or additional inertial measurement units may be present, this type of redundancy may reduce a payload of an aerial vehicle and may increase the cost for producing the aerial vehicle.
An inertial measurement unit may become less reliable on a temporary basis if the dynamics of the aerial vehicle exceeds the sensor range of the particular inertial measurement unit. For example, a sensor in the inertial measurement unit may be unable to measure a boost phase of an aerial vehicle such as, for example, a missile or a rocket. The acceleration may be so high that the sensor becomes useless for a period of time until the acceleration level decreases.
Therefore, it would be advantageous to have a method and apparatus to overcome the issues described above, as well as possible other issues.